Water Pump For Marine Engine Having Removable Cap Assembly

ABSTRACT

A water pump for a marine engine includes a drive flange for rotating a drive shaft, a housing having an internal cavity and a removable cap assembly. The removable cap assembly includes a cap lock ring secured to the housing, a cartridge extending into the internal cavity of the housing and an impeller rotatable inside the cartridge. The cap lock ring and cartridge are snap-fit together. The rotatable drive shaft has splines, which mate with a splined portion of an impeller to rotate the impeller. To replace the impeller, an operator twists the cap lock ring off the housing without any tools and pulls the cap assembly away from the housing disengaging the impeller from the drive shaft. A new cap assembly replaces the worn cap assembly.

TECHNICAL FIELD

The present invention relates generally to water pumps for marine engines, and more particularly, to a water pump for a marine engine having a removable cap assembly including an impeller.

BACKGROUND

Water pumps for marine engines generally include a flexible impeller mounted on a shaft in a pump housing for rotation therein. The flexible impeller should be replaced annually when winterizing the marine engine to prevent the rubber from being damaged due to sand, silt, seaweed and other debris along with freezing and thawing. Because a marine engine is commonly operated in salt water, the impeller may become encrusted with silt and salt. It is common to have to replace the pump impeller after every 100 hours of operation.

In conventional marine engines, the water pump is mounted in an area dark and difficult to access. To change the flexible impeller, a cover plate must be removed. Known cover plates are screwed into the pump housing. Therefore, one must use a screw driver to remove the screws holding on a cover plate before changing the flexible impeller. Due to the location of the water pump, fitting a screw driver into a tight, dark area is challenging. Once the cover plate is removed, the flexible impeller must be removed from inside the pump housing.

One method of removing the flexible impeller is to use two sets of pliers. Two impeller blades are gripped on either side using the pliers. Alternatively, a screw driver may be used to pry an impeller from inside the pump housing.

For large impellers or impellers stuck on a shaft inside the pump housing, the methods described above may not be adequate. In such situations, the user may have to remove the water pump from the marine engine and work on removing the impeller remotely which may not be practical, such as when a marine engine is being used at sea. Alternatively, a separate tool, such as one disclosed in U.S. Pat. Nos. 6,394,753 or 8,312,607, may be used. However, it is unlikely such a separate tool is carried aboard the vessel driven by the marine engine with a failed water pump.

Even when an impeller is removed and replaced, the inner surface of the water pump housing against which the impeller rubs may deteriorate over time, thereby decreasing the efficiency of the water pump. In such a situation, replacing the impeller alone does not improve the performance of the water pump for a marine engine. Often, a new water pump must be purchased and installed, which is costly and time-consuming.

Accordingly, there is a need for a water pump for use in a marine engine with a removable cartridge including an impeller which may be quickly and easily replaced without any special tools.

SUMMARY

According to an exemplary embodiment of the invention, a water pump for a marine engine includes a housing having an internal cavity having an open end. The housing has external threads surrounding a portion of the internal cavity. The water pump further comprises a drive assembly having a drive flange adapted to be rotated by the marine engine and a drive shaft. The drive shaft has splines and extends inside the internal cavity of the housing.

The water pump further comprises a cap assembly. The cap assembly comprises a cap lock ring having internal threads along a continuous sidewall and a flange defining a central opening. The internal threads of the cap lock ring engage the external threads of the housing to secure the cap lock ring to the housing. The cap lock ring has integral tabs to facilitate rotating the cap lock ring to tighten or loosen the cap lock ring relative to the housing.

The cap assembly further comprises a cartridge secured to the cap lock ring of the cap assembly. The cartridge is sized to fit inside the internal cavity of the housing. The cartridge is snap-fit to the cap lock ring and rotatable relative to the cap lock ring.

The cap assembly further comprises an impeller inside the cartridge. The impeller has a plurality of flexible blades extending radially outwardly from a central portion and a bore extending through the central portion of the impeller. The bore has a splined portion. The splined portion of the impeller bore mates with the splines of the drive shaft such that rotation of the drive shaft rotates the impeller inside the cartridge.

The cap assembly is capable of being disengaged from the housing and replaced to provide a new impeller, new cartridge and new cap lock ring. Replacement cap assemblies may be sold separately.

The water pump further comprises a hose bib cap secured to the housing, the hose bib cap comprising first and second nipples, the first nipple being adapted to couple to an inlet hose and the second nipple being adapted to couple to an outlet hose. The first and second nipples may be any desired orientation relative to each other.

According to another aspect of the invention, a water pump for a marine engine comprises a housing having an internal cavity and external threads on an open end of the internal cavity. The water pump further comprises a rotatable drive shaft having splines. The drive shaft extends inside the internal cavity of the housing.

The water pump further comprises a cap assembly comprising a cap lock ring having internal threads. The internal threads are adapted to engage the external threads on the open end of the internal cavity of the housing to close the internal cavity of the housing.

The cap assembly further comprises a cartridge secured to the cap lock ring. The cartridge is sized to fit inside the internal cavity of the housing and cover the open end of the internal cavity of the housing. The cartridge of the cap assembly has first and second openings aligned with first and second openings extending through the housing via locators on the housing and cartridge. A hose bib cap is welded to the housing to provide first and second nipples surrounding the first and second openings of the housing respectively. The first nipple is sized to couple to an inlet hose and the second nipple is sized to couple to an outlet hose. Different nipple assemblies provide different orientations of the nipples.

The cap assembly further comprises an impeller. The impeller has a plurality of flexible blades extending radially outwardly from a central portion and a bore extending through the central portion of the impeller. The impeller bore has a splined portion which engages the splines of the drive shaft such that rotation of the drive shaft rotates the impeller inside the cartridge of the cap assembly. The cap assembly is removable and replaceable without use of any tools.

According to another aspect of the invention, a water pump for a marine engine comprises a housing having an internal cavity having an open end. The housing has external threads around the open end of the internal cavity.

The water pump further comprises a drive shaft and a cap assembly. The cap assembly includes an injection molded plastic cap lock ring having internal threads adapted to engage the external threads around the open end of the internal cavity of the housing. The cap assembly further comprises a cartridge secured to the plastic cap lock ring. The cartridge has a hollow interior and is sized to fit inside the internal cavity of the housing and cover the open end of the internal cavity of the housing. The cartridge has an open bottom such that the drive shaft extends through the housing and into the hollow interior of the cartridge.

The cap assembly further comprises a rotatable impeller inside the hollow interior of the cartridge. The rotatable impeller has a plurality of flexible blades extending radially outwardly from a central portion. A bore extends through the central portion of the impeller. The bore of the impeller is adapted to engage the drive shaft such that rotation of the drive shaft rotates the impeller inside the hollow interior of the cartridge. The cap assembly is removable from the housing without tools to replace the impeller.

One advantage of the water pump of the present invention is that the impeller may be replaced quickly and easily without special tools, such as a screwdriver.

Another advantage of the water pump of the present invention is that a cap assembly, including a removable cartridge and an impeller, may be removed by hand without use of any tools.

Another advantage of the water pump of the present invention is that by replacing the cap assembly, a new impeller and new critical wear surface is provided without the need to purchase a new water pump.

Another advantage of the water pump of the present invention is that the water pump has more flow capacity than existing pumps of the same size due to the configuration of the housing including larger inlet and outlet openings, a diverging flow path in the inlet and outlet openings and a longer impeller than previously used.

Another advantage of the water pump of the present invention is that the two-piece configuration of the water pump housing allows for different inlet/outlet hose configurations.

Various additional features and advantages of the invention will become more apparent to those of ordinary skill in the art upon review of the following detailed description of the illustrative embodiments taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the general description given above and the detailed description given below, explain the embodiments of the invention.

FIG. 1 is a top view of a motorboat including an inboard engine.

FIG. 2A is a perspective view of a portion of a marine engine showing the water pump mounted to the marine engine.

FIG. 2B is a perspective view of a portion of a different marine engine showing the water pump mounted to the marine engine.

FIG. 3 is a perspective view showing the fully assembled water pump of the present invention.

FIG. 4A is a perspective partially disassembled view of the water pump showing the cap assembly separated from the remainder of the water pump.

FIG. 4B is another perspective partially disassembled view of the water pump showing the cap assembly separated from the remainder of the water pump.

FIG. 5 is another perspective partially disassembled view of the water pump showing the cap assembly separated from the remainder of the water pump.

FIG. 6 is a perspective disassembled view of the cap assembly of the water pump.

FIG. 7 is a cross-sectional view of the water pump taken along the line 7-7 of FIG. 3 showing the bearings of the water pump.

FIG. 8A is a cross-sectional view of the cap lock ring of the water pump being loosened from the open end of the housing by twisting the cap lock ring.

FIG. 8B is a cross-sectional view of the cap assembly of the water pump being pulled away from the housing to remove the impeller from inside the water pump housing.

FIG. 9 is a cross-sectional view of the water pump taken along the line 9-9 of FIG. 3 showing the impeller's configuration in use.

FIG. 10 is a perspective view of the drive assembly and impeller of the water pump showing the interaction between the two components.

FIG. 11 is a perspective view showing an alternative embodiment of water pump fully assembled and having a different hose bib cap.

FIG. 12 is a perspective view showing an alternative embodiment of water pump fully assembled and having a different hose bib cap.

FIG. 13 is a perspective view showing an alternative embodiment of water pump fully assembled and having a different hose bib cap.

DETAILED DESCRIPTION

Referring to FIG. 2A, a water pump 10, according to an exemplary embodiment of the invention, is shown mounted to a marine engine 12 within a motorboat 14. The motorboat 14 includes a bow 16, a stern 18, a port side 20, and a starboard side 22. The engine 12 is shown mounted in an “inboard” configuration and is coupled to a V-drive transmission 24 that drives a propeller shaft and propeller (not shown) to rotate, which propels the motorboat 14 through the water.

Referring to FIG. 2B, the water pump 10 is shown mounted to a different engine 12 a, the water pump being driven by a belt. The marine engines shown herein are not intended to be limiting. The water pump 10 of the present invention may be used in any marine engine.

Referring to FIG. 3, for purposes of this document, water pump 10 has a front 4 and a rear 6. FIG. 3 illustrates the water pump 10 in a fully assembled position unattached to any marine engine. When the water pump 10 is operating and water is moving through the water pump, the water pump 10 is in its fully assembled position shown in FIG. 3.

As best seen in FIGS. 4B and 5, the water pump 10 has a housing 26, which is preferably a unitary member made of injection molded plastic, but may be made of any desired material. In one preferred embodiment, the housing 26 is made of a phenolic material, which is a thermoset plastic with virtually zero creep and molding accuracy that allows for tight tolerances. One advantage of a plastic housing is that it is corrosion proof.

As best shown in FIG. 4B, housing 26 has a flange portion 80 located at the front of the housing 26, a mounting portion 30 located at the rear of the housing and a generally cylindrical cavity portion 32 between the flange portion 80 and the mounting portion 30. The housing 26 has a plurality of spaced external ribs 28 extending along the generally cylindrical cavity portion 32 and terminating in the mounting portion 30 of the housing 26. The housing 26 has an internal cavity 34 having an open end 36, which is covered with a cartridge 40 when the water pump 10 is fully assembled.

As best shown in FIG. 5, the flange portion 80 of the housing 26 has external threads 82 for engaging internal threads 84 of a cap lock ring 86 to secure the cap lock ring 86 to the housing 26 with the cartridge 40 therebetween covering the open end 36 of the internal cavity 34 of the housing 26.

The mounting portion 30 of housing 26 comprises two openings 43. Inside each opening 43 is a compression limiter 42 used to mount the water pump 10 to a marine engine, such as marine engine 12a with fasteners 44, as shown in FIG. 2B. The compression limiter 42 is commonly made of rubber, but may be made of any desired material.

As shown in FIG. 2A, the cavity portion 32 of housing 26 of water pump 10 further comprises a stabilizer portion 46 to which a stabilizing bracket 48 is attached. As best shown in FIG. 4B, an internally threaded boss 38 having internal threads (not shown) is mounted in the stabilizer portion 46 of the housing 26. A threaded fastener (not shown) is used to secure one end of stabilizing bracket 48 to the stabilizer portion 46 of the housing 26 using the internally threaded boss 38 to reduce and hopefully prevent movement of the water pump during operation.

As best shown in FIG. 4B, the cavity portion 32 of the housing 26 has a raised portion 61 comprising an inlet opening 62 and an outlet opening 63, which allow water to flow into the internal cavity 34 of the housing 26 to rotate the impeller 50 inside the cartridge 40. The raised portion 61 of the housing 26 is generally shaped like a figure eight. Each of the inlet and outlet openings 62, 63, respectively, is generally oval-shaped. However, the openings may be any desired shape; the drawings are not intended to be limiting.

As best seen in FIGS. 5 and 6, the water pump 10 further comprises an impeller 50. The impeller 50 is sized to rotate inside a hollow interior 41 of cartridge 40. The impeller 50 has a central portion 52 and a plurality of flexible blades 54 extending radially outward from the central portion 52. Although the flexible blades 54 are illustrated having a particular configuration, the drawings are not intended to limit the configuration or shape of the flexible blades.

A bore 56 extends through the impeller 50 and has a smooth portion 58 at each end and a splined portion 60 therebetween. The smooth portions 58 of bore 56, best shown in FIGS. 5 and 6, are located at the front and rear of the impeller 50. The splined portion 60 of bore 56, best shown in FIGS. 5 and 9, has internal ribs 64. The splined portion may extend the full length of the bore 56; the drawings are not intended to be limiting.

As best seen in FIGS. 4B and 5, the water pump 10 further comprises a hose bib cap 66, which is attached to the housing 26 via linear vibration welding, but may be secured by any known method such as ultrasonic welding. Linear vibration welding creates a watertight seal between the hose bib cap 66 and raised portion 61 of the housing 26. However, the hose bib cap 66 may be attached to the housing 26 via any known method, including fasteners as long as the seal therebetween is watertight.

As best seen in FIGS. 4B and 5, the hose bib cap 66 comprises a first or inlet nipple 68 having a hollow interior 69 and a second or outlet nipple 70 having a hollow interior 71 joined by a bridge 72. As best shown in FIG. 2A, an inlet hose 76 fits over the inlet nipple 68 and carries water from a raw water source (not shown), such as a lake to the water pump 10. As best shown in FIG. 2A, an outlet hose 74 fits over the outlet nipple 70 and carries water from the water pump 10 to a heat exchanger 78. As best shown in FIG. 2B, the inlet nipple 68 has a flared portion 73 to assist securing the inlet hose 76 over the first nipple 68. The outlet nipple 70 has a flared portion 75 to assist securing the outlet hose 74 over the second nipple 70. The unitary hose bib cap 66 has the inlet nipple 68 generally parallel the outlet nipple 70.

The water pump 10 further comprises a cap assembly 88 shown assembled in FIG. 5 and disassembled in FIG. 6. The cap assembly 88 comprises the cap lock ring 86, the cartridge 40, the impeller 50 and a cartridge seal 90. As shown in FIG. 7, the cartridge seal 90 fits inside a groove 92 of the cartridge 40 and abuts the flange portion 80 of housing 26. The cartridge seal 90 functions to prevent water leaks between the housing 26 and the cartridge 40 when the cap lock ring 86 is tightened around the flange portion 80 of housing 26 by a user twisting the cap lock ring 86.

As best seen in FIG. 6, the cap lock ring 86 of the water pump 10 is a unitary injection molded plastic piece having a ring-shaped body 94 defining a central opening 96 therein. The ring-shaped body 94 comprises a continuous sidewall portion 98, including indentations 99 therein to facilitate twisting the cap lock ring 86. As best shown in FIG. 6, the cap lock ring 86 further comprises a plurality of spaced inwardly directed flexible finger portions 100, which define the size of the central opening 96. As best shown in FIG. 3, the inwardly directed flexible finger portions 100 extend radially inward from the continuous sidewall portion 98. Six spaced tabs 102 are integral with the ring-shaped body 94 and extend upwardly from the continuous flange portion 100 to facilitate rotating the cap lock ring 86. Although six tabs 102 are illustrated, any number of tabs of any desired shape may be used to help rotate the cap lock ring 86.

The second component of the cap assembly 88 is cartridge 40. The cartridge 40 is generally cylindrical and sized to fit inside the internal cavity 34 of the housing 26. As shown in FIGS. 4A and 6, the cartridge 40 is a unitary member having a top 104, a continuous sidewall 106 having an interior surface or impeller interface 108 and an open bottom 110. The top 104 of cartridge 40 has a lip 91 underneath, which the flexible finger portions 100 of the cap lock ring 86 snap to secure the cartridge 40 and cap lock ring 86 together, as best shown in FIG. 7. As best illustrated in FIG. 3, the top 104 of cartridge 40 has two recesses 105 between which is an arrow 107 which aligns with the triangular shaped locator 118 described below. The top 104 of cartridge 40 covers the open end 36 of the internal cavity 34 of the housing 26 in a snap-fit connection.

As best shown in FIGS. 5 and 6, the continuous sidewall 106 of cartridge 40 has a first or inlet opening 112 and a second or outlet opening 114. Two fins 116 extend across each opening 112, 114 for stability and to prevent large undesirable objects from passing through the water pump 10. The cartridge 40 is preferably made of thermoset phenolic plastic, but may be made of any desired material.

As best shown in FIG. 6, the continuous sidewall 106 of the cartridge 40 has a triangular-shaped locator 118 extending outwardly from the continuous sidewall 106 of the cartridge 40 between the inlet and outlet openings 112, 114, respectively. As best shown in FIG. 4A, the housing 26 has a triangular-shaped receptacle 120 extending outwardly from the inside surface 122 of the housing 26. The triangular-shaped locator 118 is adapted to be received inside the triangular-shaped receptacle 120 to properly orient the cartridge 40 relative to the housing 26 and maintain such orientation. The proper orientation is required so the inlet and outlet openings 112, 114 of cartridge 40 align with the inlet and outlet openings 62, 63 of the housing 26 for water to flow through cartridge 40 and rotate the impeller 50 therein.

As best shown in FIG. 6, additional components of cap assembly 88 include two seals 128. Each of the seals 128 is preferably made of silicone rubber, but may be made of any desirable material. Each of the seals 128 fits inside a groove 162 formed around one of inlet and outlet openings 112, 114 of cartridge 40. Each of the seals 128 has spaced bumps 164, which friction-fit the seal 128 inside one of the grooves 162.

As best illustrated in FIGS. 3 and 10, the water pump 10 further comprises a drive assembly 130 comprising a drive flange 132 and a drive shaft 134 extending outwardly from the drive flange 132. As best shown in FIGS. 3 and 6, the drive flange 132 has multiple holes 136 extending through the drive flange 132. As best illustrated in FIG. 2A, fasteners 140 (only one being shown) extend through the holes 136 in the drive flange 132 and secure the drive assembly 130 to the crank shaft of a marine engine. The drive flange 132 is preferably made of a phenolic material, which is a thermoset plastic with virtually zero creep and molding accuracy that allows for tight tolerances. Although one configuration of drive flange 132 is illustrated, the drive flange 132 may have any number of holes and/or be any configuration other than as illustrated.

As shown in FIG. 2B, the water pump 10 may have a different drive assembly 131 having a different drive flange 133 specifically designed to receive and retain a drive belt of a marine engine. Otherwise, drive assembly 131 is identical to drive assembly 130. Rotation of the drive belt of the marine engine may rotate the drive flange 133 of the drive assembly 131 of the water pump 10. The drive flange 133 has no holes therethrough, and is preferably made of a phenolic material as described above. Although one configuration of drive flange 133 is illustrated, the drive flange may be any configuration other than as illustrated. Although FIGS. 3-5, 7, 9 and 11-13 illustrate drive assembly 130 being incorporated into water pump 10, drive assembly 131 may alternatively be incorporated into any of the embodiments of water pump described or shown herein.

As best illustrated in FIG. 10, the drive shaft 134 of the drive assembly 130 has a smooth portion 142 and a splined portion 144. The smooth portion 142 of the drive shaft 134 has a groove 124 therein. As best illustrated in FIGS. 4B, 7 and 10, a snap ring 126 fits inside the groove 124 of drive shaft 134 to keep the bearings 148 as described below in place. The splined portion 144 of the drive shaft 134 has a plurality of longitudinally extending ribs 146 adapted to engage with the internal ribs 64 of the splined portion 60 of the bore 56 of impeller 50, such that rotation of the drive assembly 130, regardless of how driven, rotates the impeller 50 to move water through the water pump 10.

As best illustrated in FIGS. 4B and 7, the water pump 10 further comprises a wear plate 150, which abuts the bottom of the impeller 50 and has a high wear surface to reduce friction between the impeller 50 and the wear plate 150 to protect the plastic material of the housing 26. The wear plate 150 is preferably made of stainless steel, but may be made of any desired material. As best shown in FIG. 4B, wear plate 150 has an opening 152 therein through which the drive shaft 134 passes to engage the bore 56 of the impeller 50.

As best shown in FIGS. 4B and 7, behind the wear plate 150 is a drive shaft seal 154, which has a central opening 156 aligned with the opening 152 in the wear plate 150. The drive shaft seal 154 is preferably made of silicone rubber, but may be made of any desired material. The drive shaft seal 154 sits in front of the snap ring 126 as shown in FIGS. 4 and 5.

As best illustrated in FIGS. 4B and 7, the water pump 10 further comprises a wear plate gasket 158, which abuts the wear plate 150. The wear plate gasket 158 is preferably made of silicone rubber, but may be made of any desired material. The wear plate gasket 158 functions as a spring to apply constant force to the wear plate 150 and impeller 50.

As best illustrated in FIG. 7, the water pump 10 further comprises two bearings 148, which fit inside a sleeve 160 inside the housing 26. The bearings 148 are behind the snap ring 126 and facilitate rotation of the drive shaft 134 of the drive assembly 130.

FIG. 8A illustrates the cap lock ring 86 of cap assembly 88 being rotated, such that the cap lock ring 86 is loosened from the external threads 82 of the flange portion 80 of the housing 26. FIG. 8B illustrates the cap assembly 88, including the cartridge 40 and attached impeller 50 being pulled out of the internal cavity 34 of the housing 26.

As shown in FIG. 9, the internal cavity 34 of the housing 26 has a kidney-shaped cross-section so that the blades 54 of impeller 50 are bent more in some locations than other locations. Therefore, the blades 54 of impeller 50 continue to change shape as the water pump operates. Consequently, in previous water pumps for marine engines, a portion of the inside or “cam” surface of the pump would become worn due to foreign material intrusion or dry running, i.e. wear of the impeller blades against the inside or “cam” surface of the pump. When the inside surface became uneven, the efficiency of the pump in gallons per minute is decreased. Furthermore, rotation of the impeller could vibrate the pump at which point the pump would have to be replaced. One advantage of the present invention is that the cap assembly 88 may be replaced when the inside surface of the cartridge 40 becomes worn quickly and easily without having to replace the entire pump. The ability to replace the cap assembly results in a cost savings too because the impeller and cartridge are replaced together without the need for a new pump.

FIG. 11 illustrates an alternative water pump 10 a in which all components are the same as in water pump 10, except the hose bib cap. The unitary hose bib cap 66 a of water pump 10 a comprises a first or inlet nipple 68 a having a hollow interior 69 a and a second or outlet nipple 70 a having a hollow interior 71 a joined by a bridge 72 a. An inlet hose (not shown) fits over the inlet nipple 68 a and carries water from a raw water source (not shown) such as a lake to the water pump 10. An outlet hose (not shown) fits over the outlet nipple 70 a and carries water from the water pump 10 to a heat exchanger 78 as shown in FIG. 2A. As best shown in FIG. 11, the inlet nipple 68 a has a flared portion 73 a to assist securing the inlet hose over the first nipple 68 a. The outlet nipple 70 a has a flared portion 75 a to assist securing the outlet hose over the second nipple 70 a. The unitary hose bib cap 66 a has the inlet nipple 68 a generally parallel the outlet nipple 70 a.

FIG. 12 illustrates an alternative water pump 10 b in which all components are the same as in water pump 10, except the hose bib cap. The unitary hose bib cap 66 b of water pump 10 b comprises a first or inlet nipple 68 b having a hollow interior 69 b and a second or outlet nipple 70 b having a hollow interior 71 b joined by a bridge 72 b. An inlet hose (not shown) fits over the inlet nipple 68 b and carries water from a raw water source (not shown), such as a lake to the water pump 10. An outlet hose (not shown) fits over the outlet nipple 70 b and carries water from the water pump 10 to a heat exchanger 78 as shown in FIG. 2A. As best shown in FIG. 12, the inlet nipple 68 b has a flared portion 73 b to assist securing the inlet hose over the first nipple 68 b. The outlet nipple 70 b has a flared portion 75 b to assist securing the outlet hose over the second nipple 70 a. The unitary hose bib cap 66 b has the inlet nipple 68 a generally perpendicular the outlet nipple 70 b.

Although FIGS. 11 and 12 illustrate unitary hose bib caps 66 a, 66 b, respectively, showing specific orientations of the inlet and outlet nipples, it is within the scope of the present invention that any hose bib cap may have inlet and outlet nipples at any desired orientation relative to each other. Thus, the raw water pump of the present invention may be used in different marine engines with inlet and outlet hoses to and from a heat exchanger at any desired orientation.

FIG. 13 illustrates an alternative water pump 10 c in which all components are the same as in water pump 10 a except the hose bib cap. The unitary hose bib cap 66 c of water pump 10 c has threaded interiors 69 c, 71 c within the inlet and outlet nipples 68 c, 70 c. Any of the embodiments of hob bib caps shown or described herein may have inlet and outlet nipples with threaded interiors.

While the present invention has been illustrated by the description of specific embodiments thereof, and while the embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. The various features discussed herein may be used alone or in any combination. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope of the general inventive concept. 

What is claimed is:
 1. A water pump for a marine engine, the water pump comprising: a housing having an internal cavity having an open end and external threads; a drive assembly comprising a drive flange adapted to be rotated by the marine engine and a drive shaft having splines, the drive shaft extending inside the internal cavity of the housing; a cap assembly comprising a cap lock ring, a cartridge secured to the cap lock ring and an impeller inside the cartridge, the cap lock ring having internal threads along a continuous sidewall, the internal threads of the cap lock ring engaging the external threads of the housing to secure the cap lock ring to the housing; and the cartridge of the cap assembly being secured to the cap lock ring of the cap assembly and being sized to fit inside the internal cavity of the housing, the impeller of the cap assembly having a plurality of flexible blades extending radially outwardly from a central portion, a bore extending through the central portion of the impeller, the bore having a splined portion, the splined portion of the impeller bore mating with the splines of the drive shaft such that rotation of the drive shaft rotates the impeller inside the cartridge, and wherein the cap assembly is capable of being disengaged from the housing and replaced to provide a new impeller, new cartridge and new cap lock ring.
 2. The water pump of claim 1, further comprising a hose bib cap secured to the housing, the hose bib cap comprising first and second nipples, the first nipple being adapted to couple to an inlet hose and the second nipple being adapted to couple to an outlet hose.
 3. The water pump of claim 1, wherein the housing has a mounting portion for mounting the housing to a marine engine.
 4. The water pump of claim 1, wherein the cap lock ring is rotatable relative to the cartridge of the cap assembly.
 5. The water pump of claim 1, wherein the cap lock ring and the cartridge of the cap assembly are snap-fit together.
 6. The water pump of claim 1, further comprising bearings inside the housing to facilitate rotation of the drive shaft.
 7. The water pump of claim 1, wherein the cap lock ring has integral tabs to facilitate rotating the cap lock ring.
 8. A water pump for a marine engine, the water pump comprising: a housing having an internal cavity and external threads on an open end of the internal cavity; a rotatable drive shaft having splines, the drive shaft extending inside the internal cavity of the housing; a cap assembly comprising a cap lock ring having internal threads, the internal threads of the cap lock ring being adapted to engage the external threads on the open end of the internal cavity of the housing; the cap assembly further comprising a cartridge secured to the cap lock ring, the cartridge being sized to fit inside the internal cavity of the housing and cover the open end of the internal cavity of the housing, the cap assembly further comprising an impeller, the impeller having a plurality of flexible blades extending radially outwardly from a central portion, a bore extending through the central portion of the impeller, the bore having a splined portion which engages the splines of the drive shaft such that rotation of the drive shaft rotates the impeller inside the cartridge of the cap assembly; wherein the cap assembly is removable and replaceable without use of any tools.
 9. The water pump of claim 8, wherein the cartridge has first and second openings aligned with first and second openings extending through the housing.
 10. The water pump of claim 9, further comprising a hose bib cap removably attached to the housing, the hose bib cap comprising first and second nipples surrounding the first and second openings in the housing, the first nipple being sized to couple to an inlet hose and the second nipple being sized to couple to an outlet hose.
 11. The water pump of claim 8, wherein the housing has a mounting portion for mounting the housing to a marine engine.
 12. The water pump of claim 8, wherein the cap lock ring and cartridge are snap-fit together.
 13. The water pump of claim 8, further comprising bearings inside the housing to facilitate rotation of the drive shaft.
 14. The water pump of claim 8, wherein the cap lock ring is a unitary member having tabs to facilitate rotating the cap lock ring.
 15. A water pump for a marine engine, the water pump comprising: a housing having an internal cavity having an open end, the housing having external threads around the open end of the internal cavity; a drive shaft; a cap assembly comprising a cap lock ring having internal threads adapted to engage the external threads around the open end of the internal cavity of the housing; and the cap assembly further comprising a cartridge secured to the cap lock ring, the cartridge having a hollow interior and being sized to fit inside the internal cavity of the housing and cover the open end of the internal cavity of the housing, the cartridge having an open bottom, such that the drive shaft extends though the housing and into the hollow interior of the cartridge; the cap assembly further comprising a rotatable impeller inside the hollow interior of the cartridge, the impeller having a plurality of flexible blades extending radially outwardly from a central portion, a bore extending through the central portion of the impeller, the bore being adapted to engage the drive shaft such that rotation of the drive shaft rotates the impeller inside the hollow interior of the cartridge; wherein the cap assembly is removable from the housing without tools to replace the impeller.
 16. The water pump of claim 15, wherein the housing comprises two mounting bosses for mounting the housing to a marine engine.
 17. The water pump of claim 15, the cartridge has first and second openings aligned with first and second openings extending through the housing.
 18. The water pump of claim 17, further comprising a hose bib cap secured to the housing, the hose bib cap comprising first and second nipples surrounding the first and second openings in the housing, the first nipple being sized to couple to an inlet hose and the second nipple being sized to couple to an outlet hose.
 19. The water pump of claim 15, wherein the cartridge and cap lock rings are plastic and snapped fit together.
 20. The water pump of claim 15, further comprising bearings inside the housing to facilitate rotation of the drive shaft. 